93-Z34 Lumina AC ??

[34ford]

Replaced the compressor on the 93 Lumina with the 3.4 motor. Had a terrible noise and I decided it was the clutch on the ac so I replaced the whole compressor. Problem was that it was the water pump not the ac compressor. Bad on my part. Now the problem is that I did replace it with a new unit. Vacuumed it down and put in 2 cans of 134a. With the motor running the clutch will not engage. All worked well before the compressor replacement.

Any ideals what might be going on. The clutch on the compressor has a 2 wire plug so I'm not sure if what to hook up to see if the clutch will engage. (the one on the 34 coupe has only one wire and it grounds through the housing.) Can't find any blown fuses. Swapped a couple of relays around also and that didn't help. Thought about jumpering the pressure switch but it has 3 prongs on it so that's not easy to figure out either.

thanks

[wayne petty]

i went looking for the wiring diagram for that model...

usually the BCM or the PCM controls the AC clutch...

there is usually a Pressure SENSOR in the AC system that tells the computer exactly how much pressure there is in the system...

the closest i can get in print is a 1990 pontiac GP manual... i don't have much on HVAC as i do mostly drivability issues..

if you still have a problem.. tuesday.. post.. an update to this thread.. i will dig the 1990 manual from the bottom of a big stack of manuals...

[tomslik]

clear codes yet?
some caddies won't let the a/c turn on until the code be gone...

[Mikej]

You might not have enough gas in it yet.

[34ford]

My neighbor who owns an ac refrigerant company helped me put the gas in and said that there is more than enough to activate the pressure switch.

I have not looked for any codes cause I just unhooked a good unit and replaced it with another good unit (i assume anyway.) Maybe I will have to go the local parts store and have it scanned for codes.

thanks for the input so far.

[wayne petty]

its a 93...

use a jumper wire between the A and the B terminals of this connector under the dash...
count the check engine light flashes...










to clear the codes on a 93... you just have to disconnect the battery or pull the 2 or 3 ECM fuses... there is probably just one that needs to be pulled but i don't recall which one it is right now..

[wayne petty]

did you see this post i put up about OBD1 scan tools...


http://forums.vetteweb.com/70/9096531/corvette-tech-discussion/scan-too ls-that-work-w-later-c3-and-c4-corvettes-t/index.html

[34ford]

Will try getting the flash count. Dumb question is how do I figure out the code by the flashes?? Is one long flash and 2 short ones =12 ??

Thanks for the help Wayne

[enjenjo]

one flash, pause, two flashes, pause, will be 12

[river1]

[enjenjo]

[tomslik]

[Mikej]

Do you have power to the pressure switch? Power to the Compressor? Kiss principle

[enjenjo]

You can "force" the compressor by applying power to one terminal on the plug, and grounding the other. You don't even need the engine running to do this just to check clutch operation.

[34ford]

[wayne petty]

PLEASE be careful if you intend of JUMPING the compressor clutch coil...

sometimes.. they are diode protected.. inside .. sometimes the diode is in the connector that you unplug with the end of the harness..

hook it up backwards.. by by diode protection..

just curious.. what is the 10th digit of the VIN number.???


or the production date off the door sticker.. month and year...

or both...

with the 3.4 motor it is probably a 94 not a 93.. and the AC clutch is computer controlled probably by a relay stashed under the hood someplace... '

[34ford]

Well guys I woke up early this morning and checked out some things on the car.

Mikej: we put 2 full cans of freon in the system after vacuuming it down. Yes there is power to the pressure switch. (Wayne, if I remember it was something like 5 to 6 volts.) Don't remember if we checked the power to the compressor.

Wayne: It is a 1993. Yes it has a relay for the ac clutch located on the passenger inner fender well with the other 2 for the cooling fans. Swaped it with one from one of the cooling fans and no change.

The fuse for the clutch is good as well as another listed for the HVAC.

I did disconnest he battery and hooked it back up and no change. Will check for codes next.

thanks again

bob

[wayne petty]

let me go over some of the components...

this is the AC system pressure SENDER.. not an on off switch.. this is a variable output.. its usually on a high pressure line as i recall.. after the condenser..

http://contentinfo.autozone.com/znetcs/product-info/en/US/ste/MT1297/im age/4/


this is a switch in the back of the compressor.. the system has to be empty to replace EITHER of these..

http://contentinfo.autozone.com/znetcs/product-info/en/US/ste/MT0674/im age/4/

Switch - Pressure in compressor. Double pin black - replaces Single pin white - low pressure cut-off. Compressor Mounted Switch - GM/Harrison - High Side Low Pressure Cut-Off (Black with Pigtail - Replaces Single Pin White and Light Blue Straight)

Switching Pressure: 45

there are several versions of this pressure switch listed..

http://contentinfo.autozone.com/znetcs/product-info/en/US/ste/MT0672/im age/4/

2 pin switchA/C pressure in compressor switch. Radiator fan control. Compressor Mounted Switch - GM/Harrison - Cooling Fan (Grey)

Switching Pressure: 240


http://contentinfo.autozone.com/znetcs/product-info/en/US/ste/MT0447/im age/4/


2 pin switchA/C pressure in compressor switch. High pressure cut-off. Compressor Mounted Switch - GM/Harrison - High Pressure Cut-Off (Blue - Replaces Red, Tan & Dark Orange)

Switching Pressure: 430



this is one variation of the ac clutch relay..

with care.. one can remove the cover without damaging it.. this leaves you an exposed relay that you can manually operate.. with the tip of a screw driver to close the contacts..

http://contentinfo.autozone.com/znetcs/product-info/en/US/f11/35928/ima ge/4/


this might be your AC system

http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=400634&u key_make=1024&ukey_model=14523&modelYear=1993&ukey_category =19447&ukey_driveLine=0&ukey_TrimLevel=0&ukey_modelRange=0& amp;searchString=



here is the direct image link without part numbers
http://parts.nalleygmc.com/images/parts/gm/fullsize/9310201W09-006.JPG

i just don't have a proper wiring diagram for the AC system.. to know how its all hooked up...

in the 90 manual.. it shows a low pressure switch that cuts off clutch power before the relay.. so the relay could close.. but there still would NOT be any power to the contacts in the relay to send to the clutch coil..

my best advice.. pull the cover off the relay.. or find another one that you can open.. see if when you manually close the relay contacts if the clutch engages.. this is just a circuit test.. if not.. look at the low pressure switch..

[Mikej]

If there is power to the pressure is it going thru the switch. If not you don't have enough gas in it.

[34ford]

[quote="wayne petty"]


this might be your AC system

http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=400634&u key_make=1024&ukey_model=14523&modelYear=1993&ukey_category =19447&ukey_driveLine=0&ukey_TrimLevel=0&ukey_modelRange=0& amp;searchString=


Yes wayne, this is my system.

the first pressure switch you show is what is similiar to mine. Mine has a 3 pin connector on it. It looks like 2 small blocks on the bottom and one stacked on top

O
O O the botton 2 are where I get a voltage reading. The top one jumped to either of the bottom ones yeilds 0 voltage reading.